Read the following statements concerning gestational hormones and identify the correct combination:
(I) hCG, hPL, and relaxin are produced in women only during pregnancy. (II) Relaxin is secreted by the pituitary gland during the early phase of pregnancy. (III) Levels of other hormones like cortisol, prolactin, and thyroxine increase several-fold in maternal blood during pregnancy. (IV) High maternal hormone levels are essential for supporting fetal growth and maintaining pregnancy.
Explanation: Statements (I), (III), and (IV) are correct. Statement (II) is incorrect because relaxin is secreted by the ovary during the later phase of pregnancy, not by the pituitary gland.
Question 82 of 100
📘 CLASS XII
Which of the following statements regarding the differentiation of germ layers are correct?
(I) Immediately after implantation, the inner cell mass differentiates into ectoderm and endoderm. (II) A middle layer called mesoderm soon appears between the ectoderm and endoderm. (III) These three germ layers give rise to all tissues and organs in adults. (IV) The inner cell mass contains certain stem cells which have the potency to give rise to all tissues and organs.
Explanation: All the statements are correct. After implantation, the inner cell mass differentiates into ectoderm and endoderm, followed by the appearance of the mesoderm. These three germ layers give rise to all tissues and organs, and the inner cell mass contains pluripotent stem cells.
Question 83 of 100
📘 CLASS XII
Trace the embryonic developmental milestones during pregnancy and select the correct statements:
(I) After one month of pregnancy, the embryo’s heart is formed. (II) By the end of the second month, the fetus develops limbs and digits. (III) By the end of 12 weeks (first trimester), most major organ systems, including limbs and external genitalia, are well-formed. (IV) The first movements of the fetus and appearance of hair on the head are typically observed during the fourth month.
Explanation: Statements (I), (II), and (III) are correct. Statement (IV) is incorrect because the first movements of the fetus and the appearance of head hair are observed during the fifth month (not the fourth month) of gestation.
Question 84 of 100
📘 CLASS XII
Concerning fetal development during the second trimester of pregnancy, identify the correct statements:
(I) By the end of 24 weeks (second trimester), the fetal body is covered with fine hair. (II) Eye-lids separate by the end of 24 weeks of pregnancy. (III) Eyelashes are formed by the end of about 24 weeks. (IV) The fetal heart is first formed and starts beating at the end of the second trimester.
Explanation: Statements (I), (II), and (III) are correct as they represent milestones of the 24-week stage. Statement (IV) is incorrect because the embryo's heart is formed and begins functioning much earlier, after one month of pregnancy.
Question 85 of 100
📘 CLASS XII
Read the statements below regarding the process of parturition:
(I) The average duration of human pregnancy is about 9 months, which is called the gestation period. (II) Parturition is induced by a complex neuroendocrine mechanism. (III) The signals for child delivery originate exclusively from the maternal endocrine glands. (IV) The mild uterine contractions induced during parturition are called the fetal ejection reflex.
Explanation: Statements (I), (II), and (IV) are correct. Statement (III) is incorrect because the signals for parturition originate from the fully developed fetus and the placenta, not the maternal endocrine glands.
Question 86 of 100
📘 CLASS XII
Analyze the hormonal feedback loop that controls human childbirth:
(I) The fetal ejection reflex triggers the release of oxytocin from the maternal pituitary. (II) Oxytocin acts on the uterine myometrium and causes stronger uterine contractions. (III) Stronger uterine contractions stimulate further secretion of oxytocin. (IV) This positive feedback loop continues, leading to the expulsion of the baby through the birth canal.
Explanation: All statements are correct. The process of parturition is governed by a stimulatory positive feedback reflex between uterine contractions and oxytocin secretion, which continually intensifies contractions until birth occurs.
Question 87 of 100
📘 CLASS XII
Regarding lactation and the properties of colostrum, evaluate the following statements:
(I) The mammary glands of females start producing milk toward the end of pregnancy by the process of lactation. (II) The milk produced during the initial few days of lactation is called colostrum. (III) Colostrum contains several antibodies (primarily IgA) absolutely essential to develop resistance in newborn babies. (IV) Breast-feeding is medically discouraged during the first few weeks due to neonatal digestive sensitivity.
Explanation: Statements (I), (II), and (III) are correct. Statement (IV) is incorrect because breast-feeding during the initial period of infant growth is strongly recommended by doctors to help develop immunity in the newborn.
Question 88 of 100
📘 CLASS XII
Choose the correct statement combination concerning the structure of the male scrotal sac:
(I) The scrotum is located outside the pelvic cavity. (II) It maintains a temperature that is 2–2.5°C lower than the core body temperature. (III) This lower temperature is required for the survival and maturation of Leydig cells. (IV) Failure of testes to descend into the scrotum has no effect on spermatogenesis.
Explanation: Statements (I) and (II) are correct. The scrotum maintains a temperature about 2–2.5°C lower than the normal internal body temperature. Statement (III) is incorrect because this lower temperature is specifically required for spermatogenesis, not Leydig cell survival. Statement (IV) is incorrect because normal spermatogenesis requires the testes to descend into the scrotum.
Question 89 of 100
📘 CLASS XII
Read the statements below regarding the seminiferous tubules and their lining cells:
(I) Each testicular lobule contains one to three highly coiled seminiferous tubules. (II) The tubules are lined on their inside by spermatogonia and Sertoli cells. (III) Spermatogonia undergo meiotic divisions to form haploid sperms. (IV) Sertoli cells periodically undergo mitosis to increase the total number of germ cells.
Explanation: Statements (I), (II), and (III) are correct. Statement (IV) is incorrect because Sertoli cells do not undergo division to form germ cells; they are non-germinal supporting cells that provide nutrition to the dividing germ cells.
Question 90 of 100
📘 CLASS XII
Concerning the anatomical details of the male accessory sex ducts, choose the correct statements:
(I) The seminiferous tubules open into the vasa efferentia through the rete testis. (II) Vasa efferentia leave the testis and open into the epididymis along the posterior surface of each testis. (III) The epididymis leads to the vas deferens, which descends into the scrotum. (IV) These accessory ducts store and transport sperms from the testes to the outside.
Explanation: Statements (I), (II), and (IV) are correct. Statement (III) is incorrect because the vas deferens ascends to the abdomen and loops over the urinary bladder, rather than descending into the scrotum.
